It is such a strange behaviour on my Acer Aspire 5720 system running Windows Vista Italian version.

I have been using my laptop for a year and recently it often shuts down immediately without displaying any message. I discovered that the CPU is too hot, the CPU fan is not spinning when Windows starts, but the interesting thing is that when I just turn on the computer with the Power button, the fan spins well, only after 2 seconds, when Windows Vista is launched, it's time for the CPU fan to stop.

3 Answers
3

Enter BIOS setup, wait a minute or two, and see whether the fan keeps spinning.
If it doesn't, you probably have a hardware problem.
You can also try booting to a CD (eg, Knoppix) and see whether it stops spinning.

My Dell laptop has the same problem. I have discovered the following reason for fan not working. When a CD is already present in the drive , and switch on my laptop, usually the fan wont work. As soon as i remove the CD our of the drive, fan starts functioning.